U.S. patent application number 16/957871 was filed with the patent office on 2020-10-22 for covered stent.
This patent application is currently assigned to Lifetech Scientific (Shenzhen) Co., Ltd.. The applicant listed for this patent is Lifetech Scientific (Shenzhen) Co., Ltd.. Invention is credited to Da Li, Caiping Liu, Benhao Xiao.
Application Number | 20200330215 16/957871 |
Document ID | / |
Family ID | 1000004972723 |
Filed Date | 2020-10-22 |
United States Patent
Application |
20200330215 |
Kind Code |
A1 |
Xiao; Benhao ; et
al. |
October 22, 2020 |
Covered Stent
Abstract
A stent graft comprises a plurality of wavy rings sequentially
arranged in a spaced manner, and membranes fixed to the plurality
of wavy rings, wherein the stent graft comprises, in a
circumferential direction, at least one keel region and a non-keel
region connected to the keel region, the keel region having an
axial shortening rate that is less than that of the non-keel
region, and the axial shortening rate of the keel region is 10-40%.
The stent graft can be bent in all directions, and the keel region
on the stent graft can provide a sufficient amount of an axial
support force for the stent.
Inventors: |
Xiao; Benhao; (Shenzhen,
CN) ; Liu; Caiping; (Shenzhen, CN) ; Li;
Da; (Shenzhen, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lifetech Scientific (Shenzhen) Co., Ltd. |
Shenzhen |
|
CN |
|
|
Assignee: |
Lifetech Scientific (Shenzhen) Co.,
Ltd.
Shenzhen
CN
|
Family ID: |
1000004972723 |
Appl. No.: |
16/957871 |
Filed: |
December 11, 2018 |
PCT Filed: |
December 11, 2018 |
PCT NO: |
PCT/CN2018/120323 |
371 Date: |
June 25, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61F 2002/077 20130101;
A61F 2/07 20130101 |
International
Class: |
A61F 2/07 20060101
A61F002/07 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 27, 2017 |
CN |
201711446195.2 |
Dec 27, 2017 |
CN |
201711446263.5 |
Claims
1. A stent graft, comprising a plurality of wavy rings and
membranes connected and fixed to the plurality of wavy rings,
wherein the stent graft comprises, in a circumferential direction,
at least one keel region and a non-keel region connected with the
keel region, wherein the shortening rate of the keel region is less
than the shortening rate of the non-keel region, and the shortening
rate of the keel region is from 10% to 40%.
2. The stent graft of claim 1, wherein each of the at least one
keel region covers a circumferential angle of from 15.degree. to
45.degree. on the stent graft.
3. The stent graft of claim 2, wherein the number of the at least
one keel region is two, and the two keel regions are symmetrically
disposed in the circumferential direction of the stent graft.
4. The stent graft of claim 1, wherein the wavy rings comprise
first wavy segments located in the at least one keel regions and
second wavy segments located in the non-keel region, and the wave
heights of the first wavy segments are greater than the wave
heights of the second wavy segments.
5. The stent graft of claim 4, wherein the wave height of the first
wavy segment is L1, the wave height of the second wavy segment is
L2, and L2/L1 is greater than or equal to 1/3 and less than 1.
6. The stent graft of claim 5, wherein L2 is greater than or equal
to 4 mm and less than or equal to 12 mm, and L1 is greater than or
equal to 8 mm and less than or equal to 18 mm.
7. The stent graft of claim 5, wherein the spacing between the
adjacent first wavy segments is L3, and L3/L1 is greater than or
equal to 1/4 and less than or equal to 3/2.
8. The stent graft of claim 7, wherein the first wavy segments
comprise first proximal vertices, and a connecting line between the
first proximal vertices of two adjacent first wavy segments is
parallel to the axis of the stent graft.
9. The stent graft of claim 8, wherein the first wavy segment
further comprises first supporting bodies connected with two sides
of the first proximal vertices, the first supporting bodies located
on one side of the first proximal vertices are distributed in the
axial direction parallel to the stent graft, and the first
supporting bodies located on the other side of the first proximal
vertices are disposed obliquely with respect to the axial direction
of the stent graft.
10. The stent graft of claim 1, wherein the stent graft further
comprises at least one proximal wavy ring located at an end of the
plurality of wavy rings, wherein the axial shortening rate between
the proximal wavy ring and the adjacent wavy ring is less than
10%.
11. A stent graft, comprising a first body section and a second
body section connected with the first body section, which are
distributed in the axial direction, wherein the axial shortening
rate of the first body section is from 10 to 40%, and the axial
shortening rate of the second body section is zero.
12. The stent graft of claim 11, wherein the first body section
comprises, in the circumferential direction, keel regions and a
non-keel region connected with the keel regions, wherein the axial
shortening rates of the keel regions are less than the axial
shortening rate of the non-keel region, and the axial shortening
rates of the keel regions are from 10 to 40%.
13. The stent graft of claim 12, wherein the second body section
comprises a plurality of second wave loops arranged in a spaced
manner in the axial direction and a connector connecting the
adjacent second wave loops, wherein the number of the keel regions
is two, and the two keel regions are substantially symmetrically
distributed along the connector.
14. The stent graft of claim 13, wherein each keel region covers a
circumferential angle ranging from 15.degree. to 45.degree. on the
first body section.
15. The stent graft of claim 13, wherein the first body section
comprises a plurality of first wave loops arranged in a spaced
manner, the first wave loops comprising first wavy segments located
in the keel regions and second wavy segments located in the
non-keel region, whereinthe wave heights of the first wavy segments
are greater than the wave heights of the second wavy segments, the
first wavy segments of the two keel regions are substantially
symmetrically distributed along the connector.
16. The stent graft of claim 15, wherein the spacing between two
adjacent first wavy segments is gradually reduced in a direction
from the first body section to the second body section.
17. The stent graft of claim 15, wherein the first wavy segments
comprise wave crests, wave troughs and wave rods connecting the
adjacent wave crests and troughs, and the included angle between
the wave rod of each first wavy segment close to the connector and
the axial direction of the first body section is less than the
included angle between the wave rod of the first wavy segment away
from the connector and the axial direction of the first body
section.
18. The stent graft of claim 17, wherein the included angle between
the connecting line between a midd1e point of the wave rod of the
first wavy segment close to the connector and the longitudinal
central axis of the first body section and the connecting line
between the connector and the longitudinal central axis of the
first body section ranges from 60.degree. to 90.degree..
19. The stent graft of claim 11, wherein the stent graft further
comprises a third body section connected with an end of the second
body section away from the first body section, and the axial
shortening rate of the third body section is less than the axial
shortening rate of the first body section and greater than the
axial shortening rate of the second body section.
20. The stent graft of claim 11, wherein a length of the first body
section is from 50 mm to 100 mm.
Description
FIELD
[0001] The disclosure relates to the technical field of medical
apparatuses, and in particular, to a stent graft.
BACKGROUND
[0002] An aneurysm is a common vascular disease, mostly occurring
in the elderly, which easily leads to the rupture of aortic
aneurysms and poses a great threat to the life of patients. General
surgery was considered as the only way to treat aortic aneurysms,
but this method is extremely dangerous.
[0003] With the continuous development of medical technology,
surgeries such as a minimally invasive surgery which implants a
stent graft into a human body for treatment of aortic aneurysm and
dissecting aneurysm are being used more and more. In this treatment
method, an artificial stent graft is compressed into a delivery
device, and guided into a human body along a previously implanted
guide wire, where the stent graft is released to a lesion position.
A tumor cavity is isolated to form a new blood flow channel, and
after an aneurysm loses blood flow supply, residual blood in the
tumor cavity gradually forms blood clots and is muscularized into
vascular tissues, and a tumor wall in an expanded state contracts
due to negative pressure and gradually returns to an original
state, thereby achieving the treatment of the aneurysm.
[0004] At present, the stent graft mainly includes a plurality of
metal rings which are sequentially arranged in a spaced manner, and
a membrane fixed to the plurality of metal rings to connect the
plurality of metal rings. Due to the fact that the adjacent metal
rings are merely in a flexible connection through the membrane, and
due to the lack of rigid constraints, the metal rings are easily
shortened during stent release and post-operation long-term use, so
the stent can possibly enter a tumor cavity when the stent shortens
from a distal end to a proximal end, leading to a failure to
completely cover a tumor body by the stent graft, and causing a
type I internal leakage. In order to avoid the above situation, the
prior art mostly adopts an additional rigid connector between the
adjacent metal rings to prevent the stent from shortening.
[0005] However, the rigid connector limits the bending direction of
the stent so that the stent can only be curved towards a side
facing away from the connector. As a result, the rigid connector is
usually placed on a greater curvature side of the stent. However,
blood vessels of the human body are complicated in structure and
are usually in a curved state. Since the stent cannot be bent
arbitrarily due to the rigid connector, the stent cannot be easily
adapted to the shapes of the blood vessels.
SUMMARY
[0006] The technical problem to be solved by the present disclosure
is to provide a stent graft capable of being bent in all directions
to overcome the above-mentioned defects in the prior art.
[0007] In order to solve the technical problem, the technical
solution of the disclosure is as follows:
[0008] Provided is a stent graft, including a plurality of wavy
rings and a membrane connected and fixed to the plurality of wavy
rings. The stent graft includes, in a circumferential direction, at
least one keel region and a non-keel region connected with the keel
region, wherein the shortening rate of the keel region is less than
the shortening rate of the non-keel region, and the shortening rate
of the keel region is 10-40%.
[0009] Provided is a stent graft, including a first body section
and a second body section connected with the first body section,
which are distributed in the axial direction, wherein the axial
shortening rate of the first body section is 10-40%, and the axial
shortening rate of the second body section is zero.
[0010] In summary, the stent graft of the disclosure has the
following beneficial effects: the stent graft of the application
which is of an axial compressible structure can be bent towards all
directions, the stent graft is provided with at least one keel
region and a non-keel region, the shortening rate of the stent
graft compressed in the axial direction in the keel region is less
than the shortening rate of the stent graft compressed in the axial
direction in the non-keel region, and when the stent graft is bent,
the wavy rings in the keel region are prone to abutting against
each other to form a rigid axial supporting structure on the stent
graft to prevent the stent graft from continuing to shorten,
therefore, the stent graft of the application can not only meet
various bending requirements on a stent, but can also provide
enough axial supporting force for the stent.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The disclosure will be further described in combination with
accompanying drawings and embodiments. In drawings:
[0012] FIG. 1 is a structural schematic diagram of a straight
tubular stent graft provided by a first preferred embodiment of the
present disclosure in a bent state;
[0013] FIG. 2 is a structural schematic diagram of the stent graft
shown in FIG. 1 in a natural state;
[0014] FIG. 3 is a structural schematic diagram of a bent stent
graft provided by a first preferred embodiment of the present
disclosure;
[0015] FIG. 4 is an enlarged view of a portion G of the stent graft
shown in FIG. 3;
[0016] FIG. 5 is a structural schematic diagram of a first bent
segment of the stent graft shown in FIG. 3 after being straightened
along a first profile line;
[0017] FIG. 6 is a structural schematic diagram of wavy rings of
the stent graft shown in FIG. 3 after being re-arranged in an axial
direction according to a wave spacing between the wavy rings at the
first profile line and covered with membranes;
[0018] FIG. 7 is a structural schematic diagram of the wavy rings
of the stent graft shown in FIG. 1 which abut against each
other;
[0019] FIG. 8 is a structural schematic diagram of keel regions of
the stent graft shown in FIG. 1 that are distributed on an outer
surface of the stent graft;
[0020] FIG. 9a is a schematic diagram of the stent graft shown in
FIG. 1 with a wave included angle being 60.degree.;
[0021] FIG. 9b is a schematic diagram of the stent graft shown in
FIG. 1 with a wave included angle being 90.degree.;
[0022] FIG. 9c is a schematic diagram of the stent graft shown in
FIG. 1 with a wave included angle being 130.degree.;
[0023] FIG. 10a is a schematic diagram of adjacent second wavy
segments of the stent graft shown in FIG. 1 being opposite in phase
when the adjacent second wavy segments have no overlap in the axial
direction;
[0024] FIG. 10b is a schematic diagram of the adjacent second wavy
segments of the stent graft shown in FIG. 1 being identical in
phase when the adjacent second wavy segments have no overlap in the
axial direction;
[0025] FIG. 10c is a schematic diagram of the adjacent second wavy
segments of the stent graft shown in FIG. 1 having a phase
difference when the adjacent second wavy segments have no overlap
in the axial direction;
[0026] FIG. 11 is a schematic diagram of the adjacent second wavy
segments of the stent graft shown in FIG. 1 which have overlaps in
the axial direction;
[0027] FIG. 12 is a structural schematic diagram of a stent graft
provided by a second preferred embodiment of the present
disclosure;
[0028] FIG. 13 is a structural schematic diagram of a stent graft
provided by a third preferred embodiment of the present
disclosure;
[0029] FIG. 14 is a structural schematic diagram of a stent graft
provided by a fourth preferred embodiment of the present
disclosure;
[0030] FIG. 15 is a structural schematic diagram of the stent graft
shown in FIG. 14 after being bent in a direction indicated by a
first arrow;
[0031] FIG. 16 is a structural schematic diagram of the stent graft
shown in FIG. 14 after being bent in a direction indicated by a
second arrow;
[0032] FIG. 17 is a structural schematic diagram of a stent graft
according to a fifth embodiment of the present disclosure;
[0033] FIG. 18 is a structural schematic diagram of the stent graft
shown in FIG. 17 after being expanded;
[0034] FIG. 19 is a structural schematic diagram of the stent graft
shown in FIG. 17 after being implanted into an aortic arch;
[0035] FIG. 20 is a structural schematic diagram of a stent graft
according to a sixth embodiment of the present disclosure;
[0036] FIG. 21 is a structural schematic diagram of the stent graft
shown in FIG. 20 after being expanded;
[0037] FIG. 22 is a structural schematic diagram of a stent graft
according to a seventh embodiment of the present disclosure.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0038] In order that the technical features, objects and effects of
the present embodiments may be more clearly understood, specific
embodiments thereof will now be described in detail with reference
to the accompanying drawings.
[0039] It should be noted that "distal" and "proximal" are used as
orientation words, which are customary terms in the field of
interventional medical apparatuses, the "distal" means an end away
from an operator during a surgical procedure, and the "proximal"
means an end close to the operator during the surgical procedure.
An axial direction refers to a direction which is parallel to the
connecting line of a distal center and a proximal center of a
medical apparatus; a radial direction refers to a direction
perpendicular to the axial direction; and the distance from the
axis refers to the distance reaching the axis in the radial
direction.
[0040] As shown in FIG. 1, a first preferred embodiment of the
present disclosure provides a stent graft which is substantially of
an open-ended and hollow tubular structure, the stent graft
including a plurality of wavy rings 101, and membranes 200 fixed to
the plurality of the wavy rings 101 to connect the plurality of the
wavy rings 101.
[0041] The membranes 200 are tubular cavity structures where the
midd1e is closed and the ends are opened, and made of high
molecular materials having good biocompatibility, such as e-PTFE,
PET, or the like. The membranes 200 are fixed to the plurality of
wavy rings 101 and enclosed to form a tube cavity with a
longitudinal axis, and the tube cavity serves as a channel through
which blood flows when the stent graft is implanted into a blood
vessel.
[0042] The wavy rings 101 are made of materials having good
biocompatibility, such as nickel titanium, stainless steel, or the
like. The plurality of wavy rings 101 are arranged sequentially in
a spaced-apart manner from a proximal end to a distal end, and
preferably arranged in a parallel spaced manner. Each wavy ring 101
is of a closed cylindrical structure, and includes a plurality of
proximal vertices 102, a plurality of distal vertices 103, and
supporting bodies 104 connecting the adjacent proximal vertices 102
and distal vertices 103, and the proximal vertices 102 and distal
vertices 103 are wave crests and troughs of corresponding waves,
respectively. The plurality of wavy rings 101 have the same or
similar wavy shapes, for example, the wavy rings 101 may be a
Z-shaped wave, an M-shaped wave, a V-shaped wave or sinusoidal wave
structures, or of other structures that are radially compressible
to a very small diameter. It will be appreciated that the
embodiment does not limit the specific structures of the wavy rings
101, the wave shapes of the wavy rings 101 may be set as required,
and the number of waves and the heights of the waves in each wavy
ring 101 may be set as required.
[0043] The stent graft may be prepared as follows: weaving a metal
wire into a required wave shape, the metal wire may be a
nickel-titanium alloy wire with a wire diameter of, for example,
0.35 mm; and after heat setting, surrounding two end portions of
the metal wire with a steel jacket and fixing by mechanical
pressing so that the metal wire and the steel jacket are connected
and fastened to form a metal ring. After all the wavy rings 101 are
manufactured, surfaces of the wavy rings 101 which are sequentially
arranged are covered with membranes. For example, inner surfaces
and outer surfaces of the plurality of wavy rings 101 may be
integrally covered with e-PTFE membranes so that the plurality of
wavy rings 101 are located between two membranes 200, and the
e-PTFE membranes of an inner layer and an outer layer are bonded
together by high-temperature pressing, thereby fixing the plurality
of wavy rings 101 between the two membranes. It will be appreciated
that, in other embodiments, the wavy rings 101 may also be sutured
to PET membranes.
[0044] Of course, when formed by integrally cutting a metal tube,
the wavy rings 101 are not required to be fixed1y connected by the
steel jacket. Alternatively, the wavy ring may be formed by welding
two end points of the metal wire.
[0045] Referring to FIG. 2, the stent graft includes, in a
circumferential direction, at least one keel region 100a and a
non-keel region 100b connected with the keel region 100a, the keel
region 100a and the non-keel region 100b both extending in the
axial direction of the stent graft, and the region enclosed by the
dotted lines in FIG. 2 is the keel region 100a.
[0046] The axial shortening rate of the keel region 100a of the
stent graft is less than the axial shortening rate of the non-keel
region 100b, and the axial shortening rate of the stent graft in
the keel region 100a is 10-40%.
[0047] A method for calculating the shortening rate of the stent
graft in the axial direction is as follows: taking the length of
the stent graft, which is in a straight tubular shape, in the axial
direction in a natural state as r and the diameter of the stent
graft as d1, surrounding an inner tube with the diameter of d2 (d2
is less than d1, preferably d2 is equal to 90%*d1) with the stent
graft, applying pressure F (1N.ltoreq.F.ltoreq.52N) in the axial
direction to the stent graft till the stent graft cannot shorten
anymore to obtain the total length s, and calculating the axial
shortening rate of the stent graft according to the formula
(r-s)/r.times.100%. Where: (r-s) is an available maximum shortening
value of the stent graft. The stent graft surrounds the inner tube
for shortening, so that the phenomenon that the stent graft is
folded when shortening can be effectively avoided, that is, (r-s)
of the present application is the available maximum shortening
value when the stent graft is not folded.
[0048] When the stent graft is in a frustum shape, that is, the
diameters of the two ends of the stent graft are different, the
length of the stent graft in the axial direction in the natural
state is r, the diameter of the large end is d1, the diameter of
the small end is d3, the stent graft surrounds a conical inner tube
or a frustum inner tube with the same taper as the stent graft, and
the perpendicular distance between the stent graft and the conical
inner tube or the frustum inner tube is 0.05d1. The position of the
small end of the stent graft is fixed and unchanged, the pressure F
(1N.ltoreq.F.ltoreq.2N) in the axial direction is applied to the
large end, and the total length of the stent graft when the stent
graft cannot shorten anymore is s, and thus the shortening rate of
the stent graft in the axial direction is (r-s)/r 100%. Where:
(r-s) is an available maximum shortening value of the stent graft.
The stent graft surrounds the inner tube for shortening, so that
the phenomenon that the stent graft is folded when shortening can
be effectively avoided, that is, (r-s) of the present application
is the available maximum shortening value when the stent graft is
not folded.
[0049] When the stent graft itself is manufactured into a bent
shape, as shown in FIG. 3, the stent graft includes a first bent
section 400a and a second bent section 400b, the first bent section
400a has a first profile line 401a on a greater curvature side of
the first bent section 400a and a second profile line 402a on a
lesser curvature side of the first bent section 400a, and the
second bent section 400b has a third profile line 401b on a greater
curvature side of the second bent section 400b and a fourth profile
line 402b on a lesser curvature side of the second bent section
400b. At this time, there are two methods for calculating the
shortening rate of the bent section of the stent graft. One method
is as follows: referring together to FIG. 4, by taking the first
bent section 400a as an example, partitioning the first bent
section 400a with a plane 109 perpendicular to the axial direction
of the stent graft; and cutting a plurality of notches 403 in the
membranes 200 close to the second profile line 402a. The sizes of
the notches 403 can ensure that the stent graft is straightened
along the first profile line 401a (or cutting a plurality of
notches 403 in the membranes 200 close to the second profile line
402a, so that the sizes of the notches 403 can exactly ensure that
the stent graft is straightened along the first profile line 401a).
After the first bent section 400a is straightened as shown in FIG.
5, obtaining the length r and the diameter d1 of the straightened
first bent section 400a ; then surrounding an inner tube with a
diameter of d2 (d2 is less than d1, preferably d2 is equal to
90%*d1) with the straightened first bent section 400a; applying
pressure F (1N.ltoreq.F.ltoreq.2N) in the axial direction to the
stent graft until the stent graft cannot shorten, so as to obtain
the total length s of the region B; and then calculating the axial
shortening rate of the stent graft in the region B according to the
formula (r-s)/r*100%. The other method is as follows: also by
taking the first bent section 400a as an example, re-arranging the
wavy rings 101 in the axial direction according to the wave spacing
between the wavy rings 101 at the first profile line 401a, covering
the wavy rings 101 with membranes (with the covering materials and
a selected process kept consistent with those of the original
stent), as shown in FIG. 6, and then calculating the shortening
rate according to the above-mentioned method for calculating the
shortening rate.
[0050] During the bending of the stent graft, when any one of the
keel region 100a or the non-keel region 100b reaches the available
maximum shortening value, a rigid axial supporting structure is
formed in the region to prevent the stent graft from continuing to
be bent. Referring to FIG. 7, during the bending of the stent
graft, one wavy ring 101 of the stent graft moves in the direction
of pressure together with portions of the membranes 200 fixed to
the wavy ring 101; the portions of the membranes 200 fixed to the
wavy ring 101 move together with portions of the membranes 200
distributed at the periphery of the wavy ring 101. The portions of
the membranes 200 distributed at the periphery of the wavy ring 101
will immediately pull another wavy ring 101 nearby to move towards
one side close to the wavy ring 101 until the wavy ring 101 cannot
keep moving, and at this time, a rigid axial supporting structure
is formed on the stent graft, so that the stent graft is prevented
from continuing to shorten anymore.
[0051] When the axial shortening rate of the stent graft in the
keel region 100a is less than 10%, the shortening rate of the keel
region 100a is too small, and no matter to which direction the
stent graft is bent, the keel region 100a easily reaches the
available maximum shortening value, and the keel region 100a cannot
shorten anymore, thereby restricting the stent graft from
continuing to be bent. When the axial shortening rate of the stent
graft in the keel region 100a is greater than 40%, the axial
supporting effect of the stent graft is poor, and the stent graft
may enter the tumor cavity when the distal end of the stent graft
shortens towards the proximal end of the stent graft, thus
threatening the life of a patient. When the shortening rate of the
stent graft in the keel region 100a is 10-40%, the stent graft can
be bent towards all directions to adapt to bent blood vessels, and
sufficient axial support can be provided to prevent axial
shortening for the stent graft, thus maintaining the tube cavity
shape of the stent graft. Referring to FIG. 3, the stent graft may
be continuously bent towards different directions to better adapt
to a bent blood vessel. Preferably, the axial shortening rate of
the stent graft in the keel region 100a is 20-30%.
[0052] Referring to FIG. 8, the circumferential angle covered by
the keel region 100a on an outer surface of the stent graft is
.epsilon..degree. which is greater than or equal to 15.degree. and
less than or equal to 45.degree.. When .epsilon..degree. is less
than 15.degree., the circumferential angle covered by the keel
region 100a on the outer surface of the stent graft is small, which
may lead to a poor axial supporting effect of the entire stent
graft, and the stent graft may easily swing and retract under the
impact of blood flow, finally causing the stent graft to retract
into the tumor cavity, and endangering the life of the patient.
When .epsilon..degree. is greater than 45.degree., the
circumferential angle covered by the keel region 100a on the outer
surface of the stent graft is large, which is not conducive to
stent bending. When .epsilon..degree. is greater than or equal to
15.degree. and less than or equal to 45.degree., sufficient axial
support can be provided for the stent graft, and when the stent
graft is applied to a blood vessel with greater curvature, no
folding occurs, thereby keeping the tube cavity smooth, and
enabling the stent graft to adapt to a wider range of vascular
morphology.
[0053] Preferably, the circumferential angle .epsilon..degree.
covered by each keel region 100a on the outer surface of the stent
graft is in the range of 20.degree.-30.degree.. In addition, the
number of the keel regions 100a is two, and the two keel regions
100a are symmetrically distributed in the circumferential direction
of the stent graft.
[0054] As shown in FIG. 2, the wavy rings 101 include first wavy
segments located in the keel regions 100a and second wavy segments
located in the non-keel region 100b, and the wave heights of the
first wavy segments are greater than the wave heights of the second
wavy segments. Where the wave height of the first wavy segment is
L1, the wave height of the second wavy segment is L2, and L1 and L2
meet the condition that L2/L1 is greater than or equal to 1/3 and
less than 1. When L2/L1 is less than 1/3, dense distribution of
local waves in the keel regions 100a is easily caused, which
affects the bending property of the stent graft at this position;
or sparse distribution of local waves in the non-keel region 100b
is caused, which results in a poor supporting effect of the stent
graft at this position and a high probability of deformation.
Preferably, L2 is greater than or equal to 4 mm and less than or
equal to 12 mm, which not only is conducive to processing, but also
improves the bending property of the stent graft. Specifically,
each first wavy segment includes at least one first proximal vertex
102a, at least one first distal vertex 103a, and a first supporting
body 104a connecting the adjacent first proximal vertex 102a and
first distal vertex 103a, and the second wavy segment includes at
least one second proximal vertex 102b, at least one second distal
vertex 103b, and a second supporting body 104b connecting the
adjacent second distal vertex 102b and second distal vertex 103b.
The wave height of the first wavy segment refers to the distance
between the first proximal vertex 102a and the first distal vertex
103a in the axial direction. The wave height of the second wavy
segment refers to the distance in the axial direction between the
second proximal vertex 102b and the second distal vertex 103b; and
in the illustrated embodiment, the first distal vertex 103a and the
second distal vertex 103b are located in the same plane
perpendicular to the longitudinal central axis of the stent
graft.
[0055] The distance in the axial direction between the first
proximal vertex 102a of the first wavy segment of the wavy ring 101
and the corresponding first proximal vertex 102a of the adjacent
wavy ring 101 is L3. L1 and L3 meet the condition that L3/L1 is
greater than or equal to 1/4 and less than or equal to 3/2, so that
wave distribution in the keel regions 100a is relatively uniform.
Preferably, L1 is greater than or equal to 8 mm and less than or
equal to 18 mm, and most preferably, L1 is greater than or equal to
12 mm and less than or equal to 14 mm.
[0056] Since the wavy ring 101 has at least one wave crest with
high wave height in the keel region 100a and the plurality of
distal vertices 103 are located in the same plane perpendicular to
the longitudinal axis, when the stent graft shortens, the first
proximal vertex 102a of one wavy ring 101 easily abuts against
another wavy ring 101, and the wavy rings 101 in the keel region
100a abut against each other. When the wavy rings 101 in the keel
region 100a abut against each other, a rigid axial supporting
structure is formed on the stent graft to prevent the stent from
continuing to shorten. By arranging the keel regions 100a on the
stent graft, various bending requirements of the stent graft can be
met, and sufficient axial supporting force can be provided for the
stent graft, thereby preventing the stent graft from shortening
into the tumor cavity.
[0057] In this embodiment, each first wavy segment includes one
first proximal vertex 102a therein, a connecting line between the
first proximal vertices 102a of two adjacent first wavy segments is
parallel to the axis of the stent graft, and the first supporting
bodies 104a connected with two sides of the first proximal vertex
102a are symmetrically disposed with respect to the axis of the
stent graft.
[0058] Further, the first wavy segment of the keel region 100a has
a wave included angle of 30.degree.-60.degree., and the second wavy
segment of the non-keel region 100b has a wave included angle of
70.degree.-120.degree.. The wave included angle refers to an
included angle between the supporting bodies 104 connected with the
two sides of the same proximal vertex 102 or distal vertex 103.
[0059] When in-situ fenestration is carried out on the stent graft,
a puncture device is used to puncture a small hole in the stent
graft, and the small hole is dilated to a required size by the use
of a balloon. Referring to FIGS. 9a, 9b and 9c, the wave heights of
the wavy rings 101 in FIGS. 9a, 9b and 9c are the same, and the
wave included angles are 60.degree., 90.degree. and 130.degree.,
respectively. A balloon with a diameter of D1 (preferably D1 being
3-18 mm) is used to expand a circle of the same size at the
corresponding position of each wavy ring 101, where the
corresponding position herein refers to a position where the
distance of a connecting line, in the axis direction of the stent
graft, between the circle center of the balloon and a proximal
vertex of the wavy ring 101 in each of FIGS. 9a, 9b and 9c, is
equal. The hatched lines in the figures indicate the shapes of
windows expanded by the balloon, and it can be seen from the
figures that when the wave included angle is 90.degree. or
130.degree., the windows meeting the size requirements may be
expanded, while the wavy ring 101 with the wave included angle
being 60.degree. may limit the fenestration size so that a
fenestration edge follows the wavy ring 101. In the figures, the
region of the wavy ring 101 covered by a circle with a diameter of
D2 (D2=110%D1) is a region where the wavy ring 101 supports the
fenestration edge, that is, the greater the corresponding angle
.delta. of an intersection of the wavy ring 101 and the circle with
the diameter of D2, the higher the supporting effect that the wavy
ring 101 provides for the fenestration edge. As can be seen from
the figures, the larger the wave included angle, the smaller the
corresponding angle .delta. of the intersection of the wavy ring
101 and the circle with the diameter of D2, leading to a failure to
provide sufficient support for the fenestration edge by the wavy
ring 101.
[0060] As can be seen from the above, when the wave included angle
of the wavy ring 101 in a certain region is large, the wavy ring
101 does not limit the fenestration size, thereby being beneficial
to the fenestration; however, if the wave included angle is too
large, the fenestration edge is caused to be far away from the wavy
ring 101, and the wavy ring 101 cannot provide enough support for
the fenestration edge; and if the fenestration edge lacks the
support from the wavy ring 101, the window may be further expanded
under the action of a radial force of a branch stent, finally
leading to the separation of the branch stent from the stent graft.
In addition, if the wave included angle of the wavy ring 101 is too
large, the number of waves distributed in the circumferential
direction of the stent graft in the region is too small, which is
not conducive to maintaining the tubular cavity shape of the stent
graft. However, when the wave included angle of the wavy ring 101
in a certain region is small, although enough support may be
provided for the fenestration edge, the fenestration size may be
limited, so that the fenestration size does not meet the size of a
branch vessel. In addition, the wavy ring 101 has a certain
rigidity and is not prone to deformation under the action of
external force, and after a fenestration device is abutted against
the wavy ring 101, the wavy ring 101 is easily broken, or the wavy
ring 101 is excessively displaced with respect to the membrane 200,
so that the radial supporting effect of the stent graft is
affected.
[0061] According to the application, with the arrangement of the
keel regions 100a and the non-keel region 100b with different
shortening rates in the circumferential direction of the stent
graft, and the adjustment on the wave included angles of the keel
regions 100a and the non-keel region 100b, the non-keel region 100b
can meet the requirements of in-situ fenestration, and the keel
regions 100a can meet the requirement of axial supporting force, so
that the stent graft is prevented from shortening into a tumor
cavity.
[0062] A plurality of second wavy segments of the non-keel region
100b are arranged in a spaced manner in the axial direction, and
when the adjacent second wavy segments are different in phase, the
areas available for fenestration between the adjacent second wavy
segments are different. FIGS. 10a, 10b and 10c are sequential
schematic diagrams of the adjacent second wavy segments being
opposite in phase, being identical in phase, and having a phase
difference, in the case that the wave structures and wave spacings
of the adjacent second wavy segments are identical when the
adjacent first wavy segments have no overlap in the axial
direction. The term "being opposite in phase" means that the wave
crests of the second wavy segment are opposite to the wave troughs
of the adjacent second wavy segment, the term "being identical in
phase" means that the wave crests of the second wavy segment are
opposite to the wave crests of the adjacent second wavy segment,
and the "phase difference" means that the wave crests of the second
wavy segment are staggered with the wave crests and troughs of the
adjacent second wavy segment. As can be seen from the figures, when
the adjacent second wavy segments are opposite in phase, the area
available for fenestration between the adjacent second wavy
segments is at a maximum, and when the adjacent second wavy
segments are identical in phase, the area available for
fenestration is at a minimum. However, when the adjacent second
wavy segments are identical in phase, fenestration regions are
distributed more uniformly.
[0063] In order to meet the fenestration requirement of the stent
graft, different phase conditions may be adapted by adjusting the
wave height and the ratio of the wave height to the wave spacing of
the second wavy segment of the non-keel region 100b. In the case
that the second wavy segments have no overlap in the axial
direction, when the connecting line between the wave crest of the
second wavy segment and the corresponding wave crest of the
adjacent second wavy segment is parallel to a rail of the stent
graft, the ratio of the wave height of the second wavy segment to
the spacing between the adjacent second wavy segments is 1/3-1, and
the wave height of the second wavy segment is 4-12 mm. When the
connecting line between the wave crest of the second wavy segment
and the corresponding wave trough of the adjacent second wavy
segment is parallel to the rail of the stent graft, the ratio of
the wave height of the second wavy segment to the spacing between
the adjacent second wavy segments is 1/4-3/4, and the wave height
of the second wavy segment is 4-14 mm. When the connecting line
between the wave crest of the second wavy segment and the
corresponding wave crest of the adjacent second wavy segment is
inclined with respect to the rail of the stent graft, the ratio of
the wave crest of the second wavy segment to the spacing between
the adjacent second wavy segments is 1/4-1, and the wave height of
the second wavy segment is 4-14 mm. As shown in conjunction with
FIG. 11, in the case that the adjacent second wavy segments have
overlaps in the axial direction, the ratio of the wave height of
the second wavy segment to the spacing between the adjacent second
wavy segments is 1-3, and the wave height of the second wavy
segment is 5-15 mm. The corresponding wave crest here refers to the
wave crest of the adjacent second wavy segment that has the
shortest connecting distance between the wave crest of the second
wavy segment and a wave crest of the adjacent second wavy segment
compared to other wave crests of the adjacent second wavy segment;
and the corresponding wave trough here refers to the wave trough of
the adjacent second wavy segment that has the shortest connecting
distance between the wave trough of the second wavy segment and the
wave trough of the adjacent second wavy segment compared to other
wave troughs of the adjacent second wavy segment.
[0064] As shown in FIG. 8, the non-keel region 100b includes two
sub-regions, namely a greater curvature side region 110 and a
lesser curvature side region 111, that are distributed in the
circumferential direction. The wave included angle of the greater
curvature side region 110 is 80.degree.-100.degree.,
preferably90.degree., and the wave included angle of the lesser
curvature side region 111 is 75.degree.-95.degree., preferably
80.degree.. The ratio of the wave height of the second wavy segment
on the greater curvature side region 110 to the wave height of the
second wavy segment on the lesser curvature side region 111 is
0.7-1, the ratio of the wave spacing between the adjacent second
wavy segments on the greater curvature side region 110 to the wave
spacing on the lesser curvature side region 111 is 0.7-1, and the
ratio of the area covered by the greater curvature side region 110
on the outer surface of the stent graft to the area covered by the
lesser curvature side region 111 on the outer surface of the stent
graft is 0.7-1.3. In the illustrated embodiment, the ratio of the
area covered by the greater curvature side region 110 on the outer
surface of the stent graft is equal to the area covered by the
lesser curvature side region 111 on the outer surface of the stent
graft, the wave heights of the second wavy segments on the greater
curvature side region 110 are equal, and the wave spacings between
the adjacent second wavy segments on the greater curvature side
region 110 are equal. Also, the wave heights of the second wavy
segments on the lesser curvature side region 111 are equal, and the
wave spacings between the adjacent second wavy segments on the
lesser curvature side region 111 are equal.
[0065] In the illustrated embodiment, the greater curvature side
region 110 and the lesser curvature side region 111 are disposed
opposite to each other in the circumferential direction, and the
keel regions 100a are connected between the greater curvature side
region 110 and the lesser curvature side region 111. It will be
appreciated that the non-keel region 100b may also be divided into
three or more circumferentially distributed sub-regions as desired,
the sub-regions may be arranged in a spaced manner or continuously,
and the wave shapes, the number of waves, the wave heights, and the
wave angles of the wavy segments of each sub-region may be set as
desired.
[0066] Further, referring to FIGS. 1 and 2, the stent graft further
includes at least one proximal wavy ring 101a at one end of the
plurality of wavy rings 101.
[0067] The axial shortening rate between the proximal wavy ring
101a and its adjacent wavy ring 101 is less than 10%, so as to
enhance the axial supporting effects of the end portions of the
stent graft, and to prevent the two ends of the stent graft from
causing the stent graft to swing under the impact of the blood
flow.
[0068] When the number of the proximal wavy rings 101a is two or
more, the axial shortening rate between the two or more proximal
wavy rings 101a is less than 3%, so as to enhance the axial
supporting effect of the end portions of the stent graft, and to
prevent the end portions of the stent graft from causing the stent
graft to swing under the impact of the blood flow. Preferably, the
axial shortening rate between the two or more proximal wavy rings
101a is zero.
[0069] It will be appreciated that at least one distal wavy ring
(not shown) may be disposed at the other end of the plurality of
wavy rings 101 and the axial shortening rate between the distal
wavy ring and the adjacent wavy ring 101 is less than 10%. When the
number of the distal wavy rings is two or more, the axial
shortening rate between the two or more distal wavy rings is less
than 3%, preferably 0.
[0070] Both the proximal wavy ring and the distal wavy ring are
made of materials having good biocompatibility, such as nickel
titanium, stainless steel or the like. The proximal wavy ring and
the distal wavy ring both have closed cylindrical structures. The
proximal wavy ring and the distal wavy ring may be a Z-shaped wave,
an M-shaped wave, a V-shaped wave or sinusoidal wave structures, or
of other structures that are radially compressible to a very small
diameter. It will be appreciated that not only the numbers of the
proximal wavy ring and the distal wavy ring may be set as desired,
but also the wave shapes, the number of waves, and the wave heights
of the proximal wavy ring and the distal wavy ring may be set as
desired.
[0071] Further, the stent graft further includes an anchoring bare
stent 105 located at one end or the distal end of the stent graft
and connected with the proximal wavy ring or the distal wavy
ring.
[0072] FIG. 12 shows a stent graft provided by a second preferred
embodiment of the present disclosure, which differs from the first
embodiment in that each keel region 100a includes one first
proximal vertex 102a, and the connecting line between the first
proximal vertices 102a of two adjacent wavy rings 101 is inclined
with respect to the axis of the stent graft.
[0073] FIG. 13 shows a stent graft provided by a third preferred
embodiment of the present disclosure, which differs from the first
embodiment in that the wavy ring 101 further includes a third wavy
segment in the keel region 100a. The wave height L1 of the first
wavy segment is greater than the wave height L6 of the third wavy
segment.
[0074] The third wavy segment includes at least one third proximal
vertex 102c, at least one third distal vertex 103c, and a third
supporting body 104c connecting the adjacent third proximal vertex
102c and third distal vertex 103c, and the wave height L6 of the
third wavy segment refers to the axial distance between third
proximal vertex 102c and the third distal vertex 103c.
[0075] In the illustrated embodiment, the wave height L6 of the
third wavy segment is equal to the wave height L2 of the second
wavy segment, and the first distal vertex 103a, the second distal
vertex 103b, and the third distal vertex 103c are located in the
same plane perpendicular to the longitudinal central axis of the
stent graft. It will be appreciated that, in other embodiments, the
wave height L6 of the third wavy segment and the wave height L2 of
the second wavy segment may also be unequal, and the first distal
vertex 103a, the second distal vertex 103b and the third distal
vertex 103c need not be located in the same plane perpendicular to
the longitudinal central axis of the stent graft.
[0076] FIG. 14 shows a stent graft provided by a fourth preferred
embodiment of the present disclosure, which differs from the first
embodiment in that the first supporting bodies 104a that are
connected to one side of the first proximal vertices 102a and close
to the greater curvature side region 110 are distributed in the
axial direction parallel to the stent graft, and the first
supporting bodies 104a that are connected to the other side of the
first proximal vertices 102a and close to the lesser curvature side
region 111 are disposed obliquely with respect to the axis
direction of the stent graft.
[0077] When the stent graft of FIG. 14 is bent in a direction
indicated by a first arrow 500, referring to FIG. 15, the first
supporting bodies 104a adjacent to the greater curvature side
region 110 of the adjacent first wavy segments abut against each
other to form an axial support, and the included angle between the
first supporting bodies 104a adjacent to the greater curvature side
region 110 of the adjacent first wavy segments is .eta..degree..
When the stent graft of FIG. 14 is bent in a direction indicated by
a second arrow 600, referring to FIG. 16, the first supporting
bodies 104a adjacent to the lesser curvature side region 111 of the
adjacent first wavy segments abut against each other to form an
axial support, and the included angle between the first supporting
bodies 104a adjacent to the lesser curvature side region 111 of the
adjacent first wavy segments is .theta..degree.. As can be seen
from the figures, .eta..degree. is less than .theta..degree.. When
the first supporting bodies 104a of the adjacent first wavy
segments abut against each other to form the axial support, the
greater the included angle between the first supporting bodies 104a
of the adjacent first wavy segments, the smaller the force
distributed to the axial direction of the stent graft, and the
poorer the axial supporting effect on the stent graft. Therefore,
the axial supporting effect formed when the first supporting bodies
104a are distributed parallel to the axial direction of the stent
graft abutting against each other in FIG. 15 is superior to the
axial supporting effect formed when the first supporting bodies
104a are disposed obliquely with respect to the axial direction of
the stent graft abutting against each other in FIG. 16. Meanwhile,
when the included angle between the first supporting bodies 104a of
the adjacent first wavy segments is greater, excessive deformation
of the membranes of the keel regions 100a is easily caused to bring
about an uneven surface of the stent graft, thus leading to a high
probability of thrombosis.
[0078] When the first supporting bodies 104a distributed in the
axial direction parallel to the stent graft abut against each other
to form the axial support, the included angle between the first
supporting bodies 104a of the adjacent first wavy segments is the
smallest, and the axial supporting force of the stent graft is the
highest. Therefore, the first supporting bodies 104a distributed in
the axial direction parallel to the stent graft are disposed on one
side close to the greater curvature side region 110, and when the
stent graft is bent towards the lesser curvature side, the first
supporting bodies may provide enough axial supporting force for the
stent graft, and the axial supporting effect on the stent graft is
optimal.
[0079] Referring to FIG. 17, a fifth preferred embodiment of the
present disclosure provides a stent graft 500, including a first
body section 510 and a second body section 520 connected with the
first body section 510, which are distributed in the axial
direction. The axial shortening rate of the first body section 510
is 10-40%, and the axial shortening rate of the second body section
520 is zero. The axial shortening rate of the first body section
510 is measured by a method including the following steps of: in a
natural state, taking the length of the first body section 510 as a
and the diameter as d, surrounding the first body section 510 with
an inner tube with a diameter of 0.9 d, applying pressure of 1-2N
in the axial direction to two ends of the first body section 510
until no shortening (no folding) occurs to obtain the length b, and
calculating the axial shortening rate of the first body section 510
according to the formula (a-b)*100%/a. When the length of the first
body section 510 reaches (a-b), a rigid axial support may be formed
on the first body section 510. In use, the first body section 510
is placed into a bent section (a position where the curvature
radius is smaller) of the aortic arch, and the second body section
520 is placed into a straight section (a position where the
curvature radius is greater) of the aortic arch. The first body
section 510 can axially shorten, that is, the first body section
510 has certain flexibility in the axial direction, so that the
first body section 510 generates no straightening force while
conforming to the bent configuration of the aortic arch, so that
the safety of the operation is improved. However, the second body
section 520 cannot axially shorten, so that the second body section
520 can be prevented from shortening under the action of the blood
flow, and the end portions of the second body section 520 are
prevented from retracting into the tumor cavity to endanger the
life of a patient. Preferably, the axial shortening rate of the
first body section 510 is 20-30%, so that the first body section
510 can better conform to the bent configuration of the aortic
arch, and a relatively stable axial supporting structure can be
formed, thereby reducing the risk of shortening of the first body
section 610 after implantation.
[0080] In the present embodiment, the length of the first body
section 510 is 50-100 mm, so that the first body section 510 is
able to cover the bent section in the aortic arch.
[0081] Specifically, the first body section 510 and the second body
section 520 are both open-ended and hollow straight tubular
structures. Referring together to FIG. 18, the first body section
510 includes a plurality of first wave loops 501 arranged in a
spaced manner in the axial direction and a first membrane 502
covering the first wave loops 501. The second body section 520
includes a plurality of second wave loops 503 arranged in the axial
direction, a connector 505 connecting the adjacent second wave
loops 503, and a second membrane 504 covering the second wave loops
503 and the connector 505. The first membrane 502 and the second
membrane 504 are tubular cavity structures that are closed in the
center and are open-ended, and are made of high molecular materials
having good biocompatibility, such as e-PTFE, PET, or the like. The
first membrane 502 which is fixed to the first wave loops 501, and
the second membrane 504 which is fixed to the second wave loops 503
and the connector 505, are respectively enclosed to form a tube
cavity with a longitudinal axis, and after the stent graft is
implanted into a blood vessel, the tube cavity serves as a channel
through which blood flows. The first wave loops 501, the second
wave loops 503 and the connector 505 are made of materials having
good biocompatibility, such as nickel titanium, 316L medical
stainless steel, or the like. The first wave loops 501 and the
second wave loops 503 may be a Z-shaped wave, an M-shaped wave, a
V-shaped wave or sinusoidal wave structures, or of other structures
that are radially compressible to a very small diameter. In actual
preparation, the closed first wave loops 501 and second wave loops
503 are formed by weaving nickel-titanium wires or cutting and
shaping nickel-titanium tubes, with surfaces of the first wave
loops 501 and the second wave loops 503 covered with membranes, and
the first wave loops 501 and the second wave loops 503 are
respectively fixed to the first membrane 502 and the second
membrane. 504 by means of sewing or high-temperature
pressurization, or the like.
[0082] It should be noted that the first body section 510 and the
second body section 520 are only distinguished for convenience of
explanation and do not mean that the connection boundary of the
stent graft 500 is broken, and the first body section 510 and the
second body section 520 are of an integral structure, that is, the
first membrane 502 and the second membrane 504 may be of an
integral structure.
[0083] With continued reference to FIG. 17, the first body section
510 includes, in a circumferential direction, keel regions 511 and
a non-keel region 512 connected with the keel regions 511, where
the axial shortening rates of the keel regions 511 are less than
the axial shortening rate of the non-keel region 512, and the axial
shortening rates of the keel regions 511 are 10-40%. When the first
body section 510 is bent, a rigid axial supporting structure may be
formed in the keel regions 511. Referring together to FIG. 18, the
number of the keel regions 511 is two, and the two keel regions 511
are substantially symmetrically distributed along the connector
505, so that the first body section 510 may better conform to the
anatomical structure of the aortic arch. The first body section 510
is prevented from generating additional stress and twisting forces
during bending, the first body section 510 is prevented from
swinging under the action of the blood flow, the stability of the
first body section 510 is improved in the bent state, and the life
of the stent graft 500 may be prolonged. It should be noted that
the statement that the two keel regions 511 are substantially
symmetrically distributed along the connector 505 means that the
difference between the distances from center lines of the two keel
regions 511 to the connector 505 may have a deviation of 5%.
[0084] Specifically, the first wave loops 501 include first wavy
segments 5011 located in the keel regions 511 and second wavy
segments 5012 located in the non-keel region 512, the wave height
L1 of the first wavy segment 5011 is greater than the wave height
L2 of the second wavy segment 5012, the wave spacing L3 between two
adjacent first wavy segments 5011 is less than the wave spacing L4
between two adjacent second wavy segments 5012, and the first wavy
segments 5011 of the two keel regions 511 are substantially
symmetrically distributed along the connector 505. The first wavy
segment 5011 and the second wavy segment 5012 each include wave
crests, wave troughs, and wave rods connecting the adjacent wave
crests and troughs. When the first body section 510 is bent, the
wave crests and the wave troughs of the first wavy sections 5011
abut against each other to form an axial support, and a relatively
large region for fenestration is provided between the second wavy
sections 5012, so that the implantation of a branch stent in the
region of the second wavy sections 5012 is facilitated. It should
be noted that the wave height of the present application refers to
the distance in the axial direction between a wave crest and an
adjacent wave trough, and the wave spacing refers to the axial
distance between a wave crest and a corresponding wave trough (a
wave trough closest to the wave crest) of an adjacent wave loop.
Preferably, the ratio of the wave height of the first wavy segment
5011 to the wave height of the second wavy segment 5012 is not
greater than 3, and the connecting line between the wave trough of
the first wavy segment 5011 of the first wave loop 501 and the wave
trough of the second wavy segment 5012 is perpendicular to the
plane of the axis of the first body section 510.
[0085] In the illustrated embodiment, the wave heights of the
plurality of first wavy segments 5011 are equal, and the wave
spacings between every two adjacent first wavy segments 5011 are
equal. The wave heights of the plurality of second wavy segments
5012 are also equal, and the wave spacings between every two
adjacent second wavy segments 5012 are also equal. The connecting
line of the corresponding wave crests of the plurality of first
wavy segments 5011 is parallel to the axis of the first body
section 510. Specifically, the wave height L1 of the first wavy
segment 5011 is 6-16 mm, and the wave height L2 of the second wavy
segment 5012 is 4-12 mm.
[0086] Further, in order to facilitate fenestration in the non-keel
region 512, the included angle between two adjacent wave rods of
the second wavy segment 5012 is 80.degree.-100.degree., so that the
area available for fenestration between the two adjacent wave rods
is large, and the limitation of the wave rods to the fenestration
size is reduced. Preferably, the included angle between two
adjacent wave rods of the second wavy segment 5012 is
90.degree..
[0087] Further, the phase difference of the second wavy segment
5012 is zero, that is, the connecting line between the two
corresponding wave crests of the adjacent second wavy segment 5012
is parallel to the axis of the first body section 510, and the
connecting line between the two corresponding wave troughs of the
adjacent second wavy segment 5012 is parallel to the axis of the
first body section 510. In this way, the shortest distance between
any two points on the two adjacent second wavy segments 5012 is
large, so that portions available for fenestration in the non-keel
region 512 of the first body section 510 are uniformly distributed,
the fenestration of the first body section 510 in all positions in
the non-keel region 512 is facilitated, and the implantation of the
branch stent into the first body section 510 is also
facilitated.
[0088] With continued reference to FIG. 18, the included angle
between the wave rod of the first wavy segment 5011 close to the
connector 505 and the axial direction of the first body section 510
is less than the included angle between the wave rod away from the
connector 505 and the axial direction of the first body section
510. After the stent graft 500 is released to the aortic arch, the
included angle between the wave rods of the adjacent first wavy
segments 5011 close to the connector 505 can be relatively small,
so that the force distributed to the axial direction of the first
body section 510 is relatively large, and the axial supporting
effect of the first body section 510 is improved advantageously.
Specifically, the included angle between the wave rod of the first
wavy segment 5011 close to the connector 505 and the axial
direction of the first body section 510 is not greater than
15.degree., and the included angle between the wave rod of the
first wavy segment 5011 away from the connector 505 and the axial
direction of the first body section 510 is between
20.degree.-60.degree.. Specifically, in the embodiment, the number
of the wave rods of the first wavy segment 5011 is two, the
included angle between the wave rod close to the connector 505 and
the axial direction of the first body section 510 is zero, and the
included angle between two adjacent wave rods is 30-60.degree..
[0089] Further, each keel region 511 covers an angle of
15.degree.-45.degree. in the circumferential direction, so that
damage to the membranes during bending due to excessively sharp
wave crests of the first wavy segments 5011 of the first body
section 510 may be avoided, and the risk that the first body
section 510 is folded during bending may also be reduced.
Preferably, each keel region 511 covers an angle of
20.degree.-30.degree. in the circumferential direction.
[0090] Further, the included angle between the connecting line
between a midd1e point of the wave rod of the first wavy segment
5011 close to the connector 505 and the longitudinal central axis
of the first body section 510 and the connecting line between the
connector 505 and the longitudinal central axis of the first body
section 510 is 60.degree.-90.degree., that is, the angle covered in
the circumferential direction by the non-keel region 512 which is
between the two keel regions 511 and on the side intersecting with
the extension line of the connector 505 is approximately
120.degree.-180.degree.. After the implantation of the aortic arch,
the area of the non-keel region 512 that is between the two keel
regions 511 on the first body section 510 and located on the
greater curvature side of the blood vessel can be relatively large,
so that the fenestration on the non-keel region 512 on this side
for the implantation of the branch stent is facilitated, and at the
same time, the first body section 510 can better conform to the
anatomical structure of the aortic arch.
[0091] It should be noted that the structure of the second body
section 520 may be as shown in the prior art and will not be
described in detail herein. In the illustrated embodiment, the
shapes and sizes of the second wave loops 503 are identical, and
the spacings between two adjacent second wave loops 503 are also
equal. The wave heights of the second wave loops 503 are 8-18 mm,
and the ratio of the wave spacing to the wave height of two
adjacent second wave loops 503 is not greater than 1/3. The number
of the connector 505 is one, the connector 505 is linear, and the
connector 505 spans all of the second wave loops 503 of the second
body section 520.
[0092] It will be appreciated that the second wave loops 503 of the
second body section 520 and the connector 505 may also be adjusted
according to actual needs, as long as it is ensured that the
shortening rate of the second body section 520 is zero.
[0093] Referring together to FIG. 19, in an actual operation, when
the stent graft 500 is implanted into the aortic arch, the first
body section 510 may be located at a bent portion of the aortic
arch, the second body section 520 may be located at a straight
portion of the aortic arch, the first wavy segments 5011 of the
keel regions 511 may abut against each other to form an axial
support, and reconstruction of important branch vessels of three
main arteries, including the truncus brachiocephalicus, the left
common carotid artery and the left subclavian artery, on the aortic
arch may be accomplished by means of in-situ fenestration on the
non-keel region 512 located on the greater curvature side of the
blood vessel.
[0094] Referring to FIG. 20, the structure of the stent graft 600
according to the second embodiment of the present disclosure is
substantially the same as that of the stent graft 500, except that
first wave loops 601 of a first body section 610 are arranged at
unequal intervals.
[0095] Referring together to FIG. 21, the wave spacing between
first wavy segments 6011 of a keel region 611 is gradually reduced
from an end away from the second body section 620 to an end close
to the second body section 620, so that the axial shortening rate
of the first body section 610 is gradually reduced from the end
away from the second body section 620 to the end close to the
second body section 620, gentle transition to the second body
section 620 is achieved, the risk of local compression of a vessel
wall caused by the fact that a region where the first body section
610 is connected with the second body section 620 is bulged can be
reduced, and the stability of the stent graft 600 is improved.
Further, the wave spacing between second wavy segments 6012 of a
non-keel region 612 is gradually reduced from an end away from the
second body section 620 to an end close to the second body section
620, so that a window more meeting the size requirement of a branch
vessel on the aortic arch can be conveniently opened in the
non-keel region 612, and the improvement of the stability of the
branch stent and the stent graft 600 is facilitated.
[0096] In the illustrated embodiment, the wave spacing between the
first wavy segments 6011 of the keel region 611 is an arithmetic
sequence from the end away from the second body section 620 to the
end close the second body section 620. The wave spacing between the
second wavy segments 6012 of the non-keel region 612 is an
arithmetic sequence from the end away from the second body section
620 to the end close to the second body section 620. Specifically,
from the end close to the second body section 620, the wave spacing
between the first wavy segment 6011 and the second first wavy
segment 6011 is 1 mm, the wave spacing between the second first
wavy segment 6011 and the third first wavy segment 6011 is 2 mm,
and so on.
[0097] It will be appreciated that, in other embodiments, the wave
spacing between the first wavy segments 6011 of the keel region 611
may also be adjusted as desired, so long as the shortening rate of
the keel region 611 is between 10% and 40%. The wave spacing
between the second wavy segments 6012 of the non-keel region 212
may also be adjusted according to the position and size of the
branch vessel on the aortic arch.
[0098] Referring to FIG. 22, the structure of a stent graft 700
according to a third embodiment of the present disclosure is
substantially the same as that of the stent graft 500, except that
the stent graft 700 further includes a third body section 730
connected to an end of the second body section 720 away from the
first body section 710. The axial shortening rate of the third body
section 730 is less than the shortening rate of the first body
section 710, and greater than the axial shortening rate of the
second body section 720.
[0099] Although the straight section of the aortic arch is in a
relatively gentle (relatively large curvature radius) region in the
blood vessel, due to the relatively complicated anatomical
structure of the aortic arch, a part of residual straightening
force may still exist after the implantation of the second body
section 720; and with the arrangement of the third body section 730
which has an anchoring effect with a vessel wall, a certain stretch
restriction effect may be played on the second body section 720 to
reduce the acting force of the second body section 720 on the
vessel wall, so that the risk of a rupture of the vessel wall is
reduced. In addition, the axial shortening rate of the third body
section 730 is less than the axial shortening rate of the first
body section 710 and greater than the axial shortening rate of the
second body section 720, so that the third body section 730 has a
certain bending characteristic and can be prevented from
shortening.
[0100] With continued reference to FIG. 22, the third body section
730 includes a plurality of third wave loops 707 arranged in a
spaced manner in the axial direction, and the wave spacing between
the third wave loops 707 is gradually increased from the end close
to the second body section 720 to the end away from the second body
section 720, so that a gentle transition between the second body
section 720 and the third body section 730 is achieved, thereby
reducing the risk that the stent graft 700 is bulged in use.
[0101] The structure of the third body section 730 may be similar
to the structure of the first body section 710, and is not
described in detail herein. In the illustrated embodiment, the
structure of the third wave loop 707 may be the same as that of the
first wave loop 701, and the third body section 730 with a smaller
axial shortening rate may be obtained by reducing the wave spacing
of the first wave loop 701. It will be appreciated that, in other
embodiments, the structure of the third body section 730 may also
be designed as desired, so long as the axial shortening rate of the
third body section 730 is maintained between the axial shortening
rate of the first body section 710 and the axial shortening rate of
the second body section 720. For example, the connecting line of
the wave crests of each third wave loop 707 is located in a plane
perpendicular to the axis of the third body section 730, and the
connecting line of the wave troughs is also located in the plane
perpendicular to the axis of the third body section 730.
[0102] The technical features of the above-mentioned embodiments
may be combined in any combination. In the interest of brevity, all
possible combinations of the technical features in the above
embodiments are not described, but all should be considered as
within the scope of this Description, except combinations where at
least some of such technical features are mutually exclusive.
[0103] The above-mentioned embodiments are merely illustrative of
several embodiments of the present disclosure, and the description
thereof is more specific and detailed, but is not to be construed
as limiting the scope of protection of the present disclosure. It
should be noted that several modifications and improvements can be
made by those ordinarily skilled in the art without departing from
the concept of the present disclosure, which fall within the scope
of protection of the present disclosure. Therefore, the scope of
protection of the present disclosure shall be subject to the
appended claims.
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